Waterways in rivers or other bodies of water often contain natural channels whose depth is sufficient for safe navigation. Over time, however, natural channels tend to accumulate silt on their bottoms, thereby reducing their depth. Given enough time, river action, tidal action and weather conditions, a channel can become so silted as to render it unfit for navigation. In order to keep channels navigable, dredging is used to reduce the amount of silt on the bottom of the channel. However, do to the action of water currents, dredging requires that a wider area of the channel must be dredged to be effective. As a result, even if the desired channel is only 10 or 20 meters wide, a path 30 meters or more wide would need to be dredged to ensure that the central 10 or 20 meters is clear. In many cases, water currents and tidal action cause the rapid accumulation of silt, necessitating almost annual dredging of the channel. Building walls around the channel would be too expensive, and would likely fail due to hydro-dynamic forces. Therefore, a less expensive and simple method of keeping navigation channels free from silt is required.